Refs #34074 -- Used headers argument for RequestFactory and Client in docs and tests.

docs/topics/testing/advanced.txt

@@ -152,7 +152,10 @@ example, the test suite for docs.djangoproject.com includes the following::
 
     class SearchFormTestCase(TestCase):
         def test_empty_get(self):
-            response = self.client.get('/en/dev/search/', HTTP_HOST='docs.djangoproject.dev:8000')
+            response = self.client.get(
+                "/en/dev/search/",
+                headers={"host": "docs.djangoproject.dev:8000"},
+            )
             self.assertEqual(response.status_code, 200)
 
 and the settings file includes a list of the domains supported by the project::

docs/topics/testing/tools.txt

@@ -682,7 +682,7 @@ a name of :setting:`LANGUAGE_COOKIE_NAME` and a value of the language code::
 or by including the ``Accept-Language`` HTTP header in the request::
 
     def test_language_using_header(self):
-        response = self.client.get('/', HTTP_ACCEPT_LANGUAGE='fr')
+        response = self.client.get("/", headers={"accept-language": "fr"})
         self.assertEqual(response.content, b"Bienvenue sur mon site.")
 
 More details are in :ref:`how-django-discovers-language-preference`.